Imagination is a force that can actually manifest a reality. … Don’t put limitations on yourself. Other people will do that for you. Don’t do that to yourself. Don’t bet against yourself. And take risk. NASA has this phrase that they like, "Failure is not an option." But failure has to be an option. In art and exploration, failure has to be an option. Because it is a leap of faith. And no important endeavor that required innovation was done without risk. You have to be willing to take those risks. … In whatever you are doing, failure is an option. But fear is not.

If failure has the strength to turn your life into bitterness itself, then patience has the strength to turn your life into the sweetest joy. Do not surrender to fate after a single failure. Failure, at most, precedes success.

To me the greatest moment in an experiment is always just before I learn whether the particular idea is a good or a bad one. Thus even a failure is exciting, and most of my ideas have of course been wrong.

You are responsible for all of your successes, and the lack thereof. And that is the essential point that failure, your ever-faithful friend, wants to make: that your failure could not exist without you—without your stupidity, without your lies, without your mistakes, your uselessness, your lack of faith, your ineptitude, your unjustifiable confidence in your alleged abilities, you stupid loser—failure is your only friend. Failure is your only lover. Failure is your only hope.

The acceptance of ambiguity implies more than the commonplace understanding that some good things and some bad things happen to us. It means that we know that good and evil are inextricably intermixed in human affairs; that they contain, and sometimes embrace, their opposites; that success may involve failure of a different kind, and failure may be a kind of triumph.

Sydney J. Harris, Clearing the Ground, "Learning to Live with Ambiguity" (1986).

I chose my path. You chose the way of the hero. And they found you amusing for a while... the people of this city. But the one thing they love more than a hero is to see the hero fail, fall, die trying.

Genius is often only the power of making continuous efforts. The line between failure and success is so fine that we scarcely know when we pass it — so fine that we are often on the line and do not know it. How many a man has thrown up his hands at a time when a little more effort, a little more patience, would have achieved success. As the tide goes clear out, so it comes clear in. In business sometimes prospects may seem darkest when really they are on the turn. A little more persistence, a little more effort, and what seemed hopeless failure may turn to glorious success. There is no failure except in no longer trying. There is no defeat except from within, no really insurmountable barrier save our own inherent weakness of purpose.

Elbert Hubbard, as quoted from Electrical Review (c. 1895) without further attribution in The Search for the North Pole (1896) by Evelyn Briggs Baldwin, p. 520, this was later published as part of various works by Hubbard, including FRA Magazine : A Journal of Affirmation (1915), and An American Bible (1918) edited by Alice Hubbard.

It is better to fail in originality, than to succeed in imitation. He who has never failed somewhere, that man cannot be great. Failure is the true test of greatness. And if it be said, that continual success is a proof that a man wisely knows his powers, — it is only to be added, that, in that case, he knows them to be small.

With engineering, I view this year's failure as next year's opportunity to try it again. Failures are not something to be avoided. You want to have them happen as quickly as you can so you can make progress rapidly.

Failure makes success so much sweeter, and allows you to thumb your nose at the crowds.

Wilbur Smith, The Secrets of My Success, an interview for Live magazine, the Mail on Sunday (UK) newspaper (December 5, 2010).

Never mind failures; they are quite natural, they are the beauty of life, these failures. What would life be without them? It would not be worth having if it were not for struggles. Where would be the poetry of life? Never mind the struggles, the mistakes. I never heard a cow tell a lie, but it is only a cow—never a man. So never mind these failures, these little backslidings; hold the ideal a thousand times, and if you fail a thousand times, make the attempt once more.

Every failure is a step to success. Every detection of what is false directs us towards what is true: every trial exhausts some tempting form of error. Not only so; but scarcely any attempt is entirely a failure; scarcely any theory, the result of steady thought, is altogether false; no tempting form of Error is without some latent charm derived from Truth.

William Whewell, Lectures on the History of Moral Philosophy in England, Lecture 7 (1852).

Ambition is the last refuge of the failure.

Oscar Wilde, Phrases and Philosophies for the use of the Young (1894).

Success is simply a matter of luck. Ask any failure.

Earl Wilson, as quoted in 0 to Bitch in 10 Seconds Or Less : Quips and Comebacks for Quick-Witted Women (2005) by Amy Hatch, p. 268.

Erasmus, Adagia. Chil, III. Cent. V. 8. heading. Greek proverb from Apostolius, IX. 59 b, VIII. 43. English a free translation of the same from the rendering of the Proverb applied to Baalam by the Rabbis of the Talmud. Sanhedrin. 106 a.

He ploughs in sand, and sows against the wind,
That hopes for constant love of woman kind.

And each forgets, as he strips and runs
With a brilliant, fitful pace,
It's the steady, quiet, plodding ones
Who win in the lifelong race.
And each forgets that his youth has fled,
Forgets that his prime is past,
Till he stands one day, with a hope that's dead,
In the glare of the truth at last.

Abraham Van Helsing: Nothing is too small. I counsel you, put down in record even your doubts and surmises. Hereafter it may be of interest to you to see how true you guess. We learn from failure, not from success!

A man's life is interesting primarily when he has failed—I well know. For it's a sign that he tried to surpass himself.

Georges Clemenceau, conversation with Jean Martet, June 1, 1928—Clemenceau, The Events of His Life as Told by Himself to His Former Secretary, Jean Martet, trans. Milton Waldman, chapter 30, p. 220 (1930).

I have no use for men who fail. The cause of their failure is no business of mine, but I want successful men as my associates.

John D. Rockefeller. Silas Hubbard, John D. Rockefeller and His Career, p. 72 (1904). Hubbard states that this was a favorite saying of Rockefeller's.

It is hard to fail, but it is worse never to have tried to succeed.

Theodore Roosevelt, governor of New York, speech before the Hamilton Club, Chicago, Illinois, April 10, 1899. The Strenuous Life (vol. 13 of The Works of Theodore Roosevelt, national ed.), chapter 1, p. 320 (1926).

Ambition is the last refuge of the failure.

Oscar Wilde, "Phrases and Philosophies for the Use of the Young," The Complete Works of Oscar Wilde, vol. 10, p. 213 (1923).